KP1₄563 Gene,Transcriptional Regulation By Camp Receptor Protein,controls Type 3 Fimbrial Function In Klebsiella Pneumoniae NTUH-K2044

Purpose: Klebsiella pneumoniae?K.pneumoniae?is an opportunistic pathogen that adheres to host cells or to the extracellular matrix by the type 1 and type 3 fimbriae.KP1₄563 of K.pneumoniae NTUH-K2044 is a hypothetical protein-encoding gene.KP1₄563 is located between the type 1 and type 3 fimbrial gene clusters and is likely associated with fimbrial function given its putative conserved domains of unknown function?DUF1471?.The c AMP receptor protein?CRP?regulates virulence-related gene expression and is a crucial transcriptional regulator in many bacteria.The predicted DNA recognition motif of CRP is present in the KP1₄563 promoter region.This study aimed to investigate the function of KP1₄563 in fimbriae and its transcriptional regulation by CRP.Methods: We generated Kp-?4563 mutant strain and Kpc-?4563 complementation strain.The role of KP1₄563 in fimbriae was evaluated by phenotype and adhesion assays.We conducted lac Z fusion,electrophoretic mobility shift and DNase I footprinting assays to study the transcriptional regulation of KP1₄563 gene by CRP.Results: We found that KP1₄563 negatively regulates the function of type 3 fimbriae.Compared with NTUH-K2044,the absence of KP1₄563 enhanced the ability of Kp-?4563 adhere to A549 cells.CRP negatively regulates KP1₄563 by directly binding to its promoter region.Conclusions: KP1₄563 plays an important role in type 3 fimbrial function.This novel insight can potentially assist the development of strategies for preventing K.pneumoniae infection.